Like the biliary trematode parasites of animals and man, Hymenolepis microstoma, a tapeworm of rodents, resides in the bile duct and elicits a dramatic histological host response. The theory, on which this proposed research is based, is that these histological changes are accompanied by biochemical changes in the host. The main objectives of the proposed research are (1) to determine the exact nature and extent of these biochemical changes, (2) to correlate biochemical and histological changes, and the development of this parasite in the definitive host (the laboratory mouse), and (3) to attempt to determine the physical and/or chemical mechanism which initiates the biochemical and histological response. Experiments of the proposed research are designed to examine the alterations in amino acid, carbohydrate, lipid, protein, and nucleic acid content of liver, biliary, and intestinal tissues, and bile, from infected and control (uninfected) mice. Standardized techniques for bile and tissue fractionation, in conjunction with chromatographic techniques (TLC AND GLC) and qualitative and quantitative chemical analyses, will be used to elucidate these changes. Incorporation rates of specific radiobiochemicals will be used to determine "turnover" rates of these specific fractions during the course of the infection. All studies will be conducted using mice infected for increasing periods of time. Thus, biochemical changes may be correlated through time with the development of the parasite, and the progressive histopathology. Since many aspects of H. microstoma infections in mice and biliary trematode infections in man and animals are similar, the proposed research should provide a better understanding of the host-parasite relationships of, and the patho-biochemical changes induced by, biliary parasites in general, some of which are of medical and/or economic importance.